Is there alpha-tubulin in the nucleus?

I recently used alpha-tubulin to see if there was cytoplasmic contamination in my nuclear extracts and the corresponding band appeared. So there are two hypotheses: either my extracts are contaminated (can anyone suggest me a protocol to prepare nuclear extracts that guarantees no cytoplasmic contamination?) or alpha-tubulin is present in the nucleus. I'm hoping someone knows the answer. By the way, I use a monocytic cell line ( THP-1).
Thanks in advance

I found an extraction protocol suggested by Sigma. It is not very different from the one I use by I'll try. I send it in attachment in case you want to take a look and give your opinions.
Back to alpha-tubulin, I would like to test it in a commercial nuclear extract sample to know, for sure, if this protein exists in nucleus. Do you know any company that sells this kind of product?

I recently used alpha-tubulin to see if there was cytoplasmic contamination in my nuclear extracts and the corresponding band appeared. So there are two hypotheses: either my extracts are contaminated (can anyone suggest me a protocol to prepare nuclear extracts that guarantees no cytoplasmic contamination?) or alpha-tubulin is present in the nucleus. I'm hoping someone knows the answer. By the way, I use a monocytic cell line ( THP-1).Thanks in advance

We use that antibody and it should not appear in the nuclear fraction. One thing you should do in to wash extensively between the citosolic extraction and the nuclear extraction. So you precipitate the nuclei and you collect the citosolic fraction right? and then you wash the nuclei before the nuclear extraction; you can wash more times to be sure you are getting rid of the citosolic fraction.

"He must be very ignorant for he answers every question he is asked" Voltaire